Under normal circumstances, blood moves up the legs due to muscle contraction and general movement of the feet or legs, such as when walking. If a person is immobilized, unable to move regularly, or has poor circulation brought on by disease, the natural blood return mechanism is impaired, and circulatory problems such as ulcers, deep vein thrombosis, and pulmonary embolisms can occur.
To mitigate the problems caused by low mobility and poor circulation, it is desirable to enhance circulation through alternative means, for example means mimicking the effects of walking or otherwise increasing circulation.